Method for employing decolorizing carbons and other adsorbing materials



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JOSEPH FERG'US BREWSTER, OF CLARENDON, VIRGINIA, AND WILLIAM G. MINES,JR, OF JACKSON, MISSISSIPPI, ASSIGNORS BY DIRECT AND MESNE ASSIGNMENTS,TO THE GOVERNMENT OI THE UNITED STATES AND TO THE PEOPLE OF THE UNITEDs'ra'rns.

HETHOD ronEMrLoYme DECOLORIZING cannons AND OTHER ansomame ma'rnamrs. v

No Drawing.

Application filed April 19, 1921. Serial No. 462,764.

(FILED UNDER THE ACT OF MARCH 3, 1883, 22 STAT. L, 625.) v

To all-whom it may concern:

Be it known that we, Josnrn- America and an employee of the Departmentof Agriculture, residing in Clarendon, Virginia, and WILLIAM G. RAINES,Jr., a citizen ofthe United States of America, re-' siding in Jackson,Mississippi, have jointly invented a Method for EmployingDecolorterials.

This application is made under the act States without payment to us ofany royalty thereon. We hereby dedicate the same to the free use of theGovernment and the people of the United States.

The object of our invention is to improve the purifying and decolorizingeffect of animal charcoalor other decolorizing carbons, diatomaceousearth, fullers earth, and jlike for the purpose I-of purifying ordecolorizing liquids or solutions, particularly saccharine liquors suchas cane juice and cane syrup 80 ing of cane sugar and syrup, the juice,syrup and molasses obtained from the sugar beet, maltose, glucose andsweet potato syrup and the like, by adjusting the hydro en or hydroxylion concentration of the liquid to be purified or decolorized to anoptimum by addition of acid or alkali as required;

A further object of the invention is to provide means for controllingconditions of acidity or alkalinity durin or after treatment of liquidswith adsorbing material so that undue decomposition is prevented.

The principle of our invention is based upon the discovery thatcolloidal impurlties and'colorin matters occurring in the above namedsacc arine products are coa lated, precipitated or otherwiserendere morethoro ighly adsorbed upon decolorizing carbone and other adsorbentmaterial by adjustment of the hydogen or hydroxyl 1011 Fitness BREWSTER,a citizen of the United States of izing Carbons and Other Adsorbing Maadsorbing materials, when these are used and molasses in the manufactureand refinconcentration to an optimum for the particular liquid to bepurified or decolorized. The novelty of our invention consists in addingacid or alkali, as the case requires, ,7

to the liquid to be purified or decolorized until the particularhydrogen or hydroxyl ion concentration, or, in other words, theparticular acidity or alkalinity, has been reachedat which theimpurities and coloring matters are mostjreadily removed by theadsorbent. The optimum reaction at which any given liquid may be thuspurified or decolorized is readilyiound by experiment, 7

the well known colorimetric or electrometric methods for thedetermination of hydrogen or hydroxyl ions being empl oyed.

A further novelty of the process lies in neutralizing acidity oralkalinity in such a way that the enhanced urifying or decolorizingeffect of the adsor ent is not lost. We accomplish this by employingacids and alkalis which, by combining, form insoluble compounds, thelatter being removed with the adsorbing material. For instance, when weacidity with phosphoric acid we neutralize with lime, obtaininginsoluble calcium phosphate. If. we use sulphuric acid we neutralizewith barium hydroxide-or barium carbonate. In cases vwhere it becomesnecessary to treat in alkaline mediums the process may be reversed. Thatis, alkalinlty is obtained by means of lime which in turn is neutralizedback with phosphoric acid; or barium oxide or hydroxide with sulphuric,acid. This is an advantage over using acids and bases which form solublecompounds because the latter can not .be readily removed and wouldremain throughout later treatment.

In the operation of our process for 1mproving the efi'ect of anadsorbing medium such as decolorizing carbon the reaction of the liquidto be purified or decplorlzed is adjusted by the addition of acld suchas hydrochloric, sulphuric, phosphoric, acetic, or other acid, dependinon the acidity to ,be obtained, or of alkah such as sodium or hydroxide,sodium carbonate, for alkalinity. For the treatment we syrup and thelike, it was found that with decolorizing carbons, best purification anddecolorization takes place at a hydrogen ion concentration of about pH-4 (Sorensens scale) although good results may also be from adsorbenteither hot or cold as required.

Some su ars are decom osed or h drolyze d when their solutions areheated with acids. This applies particularly! to solutions of sucrose,the principal sugar of sugar cane and sugar beet. The extent ofinversion, which means-loss of sucrose, depends upon three factors,namely, (1) the strength of acid employed or in reality, the hydrogenion concentration of the solution, (2) the temperature to "which theacidified solution is heated and (3) the length of time the acidifiedsucrose solution is heated. In applying our invention to thepurification and decolorization of cane or sugar beet products we takethese factors into account and adjust the hydrogen ion.concentration toabout p H4 at which there is little. inversion of sucrose and at whichgood practical results can .be obtained. To control both the factors ofhydrogen ion concentration and time to which a liquid is exposed toacidreaction we proceed somewhat as follows: The liquid to be purifiedor decolorized with decolorizing carbon may, for instance, be acldlfiedto about p H-4 with an acid such as phosphoric or an acid reactingsubstance such as calcium acid phosphate. It is then treated with thecarbon andheated to the' desired temperature (80 to 100 C.) at the sametime being stirred as in the usual'practice. Adsorption of coloringmatter and other impurities by the carbon occurs andthe free acidity isthen partially neutralized by adding lime until the hydrogen ionconcentration has been reduced to about I-I-6 or 65. Wherephosphoricacid or calcium acid phosphate has been used the excess phos-\ phoneacid is'render'ed insoluble by addition of lime and is precipitated astricalcium phosphate, which may then be removed with the carbon byfiltration.

For the purification and decolorization of solutions of many othersubstances by means of adsorbents it is not always necessary to controlso carefully acidity or other factors.

This is particularly true in the case of glucose solutions or syrups. Inthe case of maltose solutions there is less danger of inversion at p H-l than with surcose solutions.

By slightly acidifying saccharine solutions before these are treatedwith an adsorbing medium, such as decolorizing carbon, diatomaceousearth, etc.. for the pur-' tained at p H-4 than at p H-5, and much.

greater at p H-5 than at p H-7 (neutrality) or at p H-8 .(slightlyalkaline).

J Examples.

1. A dilute sweet potato syrup containing sucrose, maltose and possiblya small amount of glucose, and of a deep brown. color, was dividedintothree portions, one of which was acidified to p H4, one neutralized toH-7, and the other rendered alkaline, p I-8. These solutions were thenbrought just to boiling after 1 'per cent of their weight ofdecolorizing carbon had been added and then immediately filtered. Thesolution at p H4 by this treatment was rendered a ale straw yellowalmost white. That, at p -7 showed ver slight decolorization while at pH-8, or a kaline, the solution was actually darkened bythe originaladdition of alkali and none of the color seemed to be removed bytreatment with decolorizing carbon and filtering. 2. Sugar cane juicecontaining sucrose and a small amount of invert sugar was treated withdecolorizing carbon, heated and filtered, after the hydro en ionconcentration of several portions ad been adjusted respectively, to pH-et, p.H-5.4, p H-7, and p H -8. Colorimetric readings on the severalfiltrates showed that the decolorization was greatest in the solutionwith the highest acidity, p H4, and lowest in the slightly alkalinesolution, also that removal of color progressed with increase ofacid-ity.

We claim: I A method for employing decolorizing carbone and otheradsorbing materials in a more efiicient manner, consisting in adding tothe liquid to be purified and decolorized by treatment with an adsorbingmaterial, a sufficient quantity of acidto, increase the acidity of saidliquid to a hydrogen ion concentration of about p I-I-4, in treatingsuch acidified liquid with adsorbing material, and subsequentlyneutralizing the acidity of said liquid 'b addin alkali.

J SEPH ERGUS BREWSTER.

1 WILLIAM RAINES, JR.

